The chemical amplification-type photosensitive composition is a pattern forming material capable of producing an acid in the exposed area upon irradiation with radiation such as far ultraviolet light and through a reaction using this acid as the catalyst, changing the solubility in a developer between the area irradiated with actinic radiation and the non-irradiated area, thereby forming a pattern on a substrate.
In the case of using a KrF excimer laser as the exposure light source, a resin having small absorption in the region of 248 nm and having a basic skeleton of poly(hydroxystyrene) is predominantly used as the main component, and this is an excellent system capable of forming a good pattern with high sensitivity and high resolution as compared with the conventional naphthoquinonediazide/novolak resin system.
In the case of using a light source of emitting light at a shorter wavelength, for example, in using an ArF excimer laser (193 nm) as the light source, the compound having an aromatic group substantially has large absorption in the region of 193 nm and therefore, a satisfactory pattern cannot be formed even by the above-described chemical amplification system.
In order to solve this problem, a resist containing a resin having an alicyclic hydrocarbon structure has been developed for use with an ArF excimer laser. Also, as for the photoacid generator capable of producing an acid in the exposed area upon irradiation with radiation such as far ultraviolet light, various compounds have been developed and, for example, a sulfonium salt compound having a specific substituent is disclosed (see, WO 00/08525 (corresponding to U.S. Pat. No. 6,358,665 B1), and JP-A-2000-47387 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”)).
However, in view of integrated performance as the resist, an appropriate combination is actually very difficult to find out for the resin, photoacid generator, additive, solvent and the like used. Moreover, at the time of forming a fine pattern with a line width of 100 nm or less, even when the resolving performance is excellent, this is still insufficient in terms of pattern collapse that the line pattern formed collapses and works out to a defect at the production of a device or in terms of difference in the performance between dense pattern and isolated patter, particularly, the film loss of isolated pattern.